WO2023007803A1 - Air-conditioning device - Google Patents

Abstract

In this air-conditioning device, indoor units each comprise a temperature sensor that measures a first temperature, which is a temperature of air for exchanging heat with a heat medium using an indoor heat exchanger, and a control device performs first control in a cooling/heating mixed operation mode in which a third heat-medium heat exchanger is used for cooling if an indoor unit having the largest difference between the first temperature measured by the temperature sensor and a target temperature of the indoor unit is performing a cooling operation, and the third heat-medium heat exchanger is used for heating if the indoor unit having the largest difference thereof is performing a heating operation.

Description

air conditioner

The present disclosure relates to an air conditioner capable of mixed cooling and heating operation.

A refrigerant circulation circuit that connects the outdoor unit and the relay unit with piping to circulate the heat source side refrigerant, and a heat medium circulation circuit that connects the relay unit and the indoor unit with piping to circulate the heat medium that is the indoor side refrigerant. There is an air conditioner having a circuit. In the air conditioner as described above, as shown in Patent Document 1, two heat medium heat exchangers that exchange heat between the heat source side refrigerant and the heat medium are provided in the relay unit, and a pump that conveys the heat medium to the indoor unit. There are two

In Patent Document 1, during mixed operation of cooling and heating, one heat medium circulation circuit having a heat medium heat exchanger used on the cooling side and a pump that conveys the heat medium, and a heat medium heat exchange used on the heating side There is one heat carrier circulation circuit comprising a vessel and a pump for conveying the heat carrier.

Japanese Patent No. 6095764

In conventional air conditioners, during mixed operation of cooling and heating, when the load of either cooling or heating is large and the load is unbalanced, only one combination of heat medium heat exchanger and pump can be used for cooling or heating. Therefore, the capacity of the high load side is insufficient, and the capacity of the low load side is excessive.

Therefore, efficient operation according to the cooling or heating load cannot be performed, and comfort is likely to be impaired due to insufficient capacity on the indoor unit side.

The present disclosure has been made in view of the above circumstances, and enables efficient operation according to the cooling or heating load even during load imbalance, and maintains comfort on the indoor unit side. An object of the present invention is to provide an air conditioner.

An air conditioner according to the present disclosure includes a compressor, an outdoor unit that outputs a refrigerant compressed by the compressor to a refrigerant pipe, and the outdoor unit and the refrigerant pipe that flow through the refrigerant pipe. a relay unit for exchanging heat between a refrigerant and a heat medium flowing through a heat medium main pipe; and an indoor unit having an indoor heat exchanger connected to the heat medium main pipe of the relay unit via a heat medium branch pipe. , a controller for controlling the outdoor unit, the relay unit, and the indoor unit, wherein the relay unit controls the refrigerant output from the outdoor unit to the refrigerant pipe and the heat medium flowing through the heat medium main pipe. and a second heat medium heat exchanger that performs heat exchange between the refrigerant output from the outdoor unit to the refrigerant pipe and the heat medium flowing through the main heat medium pipe. and a third heat medium heat exchanger for exchanging heat between the refrigerant output from the outdoor unit to the refrigerant pipe and the heat medium flowing through the main heat medium pipe, wherein the indoor units are plural. wherein, in a cooling/heating mixed operation mode, the control device obtains the cooling load of the plurality of indoor units and the heating load of the plurality of indoor units, and the obtained cooling load is equal to the obtained heating load. If it is greater than, use the third heat medium heat exchanger for cooling, and if the obtained cooling load is equal to or less than the heating load, use the third heat medium heat exchanger for heating, The indoor unit includes a temperature sensor that measures a first temperature, which is the temperature of air heat-exchanging with the heat medium in the indoor heat exchanger, and the control device controls the temperature sensor in the cooling/heating mixed operation mode. When the indoor unit having the largest difference between the first temperature measured by and the target temperature of the indoor unit is performing cooling operation, the third heat medium heat exchanger is used for cooling. When the largest indoor unit is performing heating operation, first control is performed to use the third heat medium heat exchanger for heating.

According to the present disclosure, when the cooling load is greater than the heating load, the third heat medium heat exchanger is used for cooling, and when the cooling load is less than or equal to the heating load, the third heat medium heat exchanger is used for heating. use as Therefore, even when the load on the indoor unit side is unbalanced, efficient operation can be performed according to the cooling or heating load, and comfort can be maintained in the indoor unit.

1 is a schematic diagram showing an arrangement example of an air conditioner according to Embodiment 1. FIG. 1 is a diagram showing the configuration of an air conditioner according to Embodiment 1. FIG. FIG. 2 is a circuit diagram showing flows of refrigerant and heat medium during cooling only operation of the air conditioner according to Embodiment 1; 3 is a circuit diagram showing the flows of refrigerant and heat medium during full-warm operation of the air conditioner according to Embodiment 1. FIG. FIG. 4 is a circuit diagram showing the flow of refrigerant in the cooling-main operation mode of the air conditioner according to Embodiment 1; FIG. 3 is a circuit diagram showing the flow of refrigerant in the heating main operation mode of the air conditioner according to Embodiment 1; 4 is a diagram showing a flowchart for determining whether to use the third heat medium heat exchanger for heating or cooling in the cooling/heating operation mode of the air conditioner according to Embodiment 1. FIG. 4 is a flowchart of a modified example for determining whether to use the third heat medium heat exchanger for heating or cooling in the cooling/heating operation mode of the air conditioner according to Embodiment 1. FIG. 4 is a flow chart of a second modified example for determining whether to use the third heat medium heat exchanger for heating or cooling in the cooling/heating operation mode of the air conditioner according to Embodiment 1. FIG. FIG. 3 is a diagram showing the configuration of an air conditioner according to Embodiment 2; FIG. 9 is a diagram showing a flowchart for explaining the operation in the cooling/heating operation mode of the air conditioner according to Embodiment 2; 10 is a flowchart of a modification for determining whether to use the third heat medium heat exchanger for heating or cooling in the cooling/heating operation mode of the air conditioner according to Embodiment 2. FIG. FIG. 10 is a diagram showing the configuration of an air conditioner according to Embodiment 3; FIG. 10 is a diagram showing a flowchart for explaining the operation in the cooling/heating operation mode of the air conditioner according to Embodiment 3; 10 is a flowchart of a modification for determining whether to use the third heat medium heat exchanger for heating or cooling in the cooling/heating operation mode of the air conditioner according to Embodiment 3. FIG.

An air conditioner according to an embodiment will be described below with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description is given only when necessary. The present disclosure may include any combination of configurations that can be combined among the configurations described in each of the following embodiments.

Also, in each figure, the same reference numerals are the same or equivalent, and this is common throughout the specification. Further, in the following embodiments, a plurality of constituent elements are distinguished from each other by adding Roman letters to the end of the reference numerals of the constituent elements. When a plurality of constituent elements are collectively explained, or when one of the constituent elements is explained as a representative, the explanation will be given without using Roman letters.

Embodiment 1.
FIG. 1 is a schematic diagram showing an arrangement example of an air conditioner 100 according to Embodiment 1. FIG. An arrangement example of the air conditioner 100 will be described based on FIG. 1 .

This air conditioner 100 has a heat source side refrigerant circulation circuit A (see FIG. 2), which is a refrigeration cycle for circulating a heat source side refrigerant, and a heat medium circulation circuit B (see FIG. 2), which is a refrigeration cycle for circulating a heat medium. . Then, the indoor unit 3a, the indoor unit 3b, and the indoor unit 3c use the heat source side refrigerant circulation circuit A and the heat medium circulation circuit B, so that the cooling mode, the heating mode, or the mixed cooling and heating mode can be freely selected as the operation mode. It's like FIG. 1 schematically shows an overall air conditioner 100 connecting three indoor units 3 . In addition, in the following drawings including FIG. 1, the size relationship of each component may differ from the actual size.

In FIG. 1, an air conditioner 100 according to Embodiment 1 includes an outdoor unit 1 which is a heat source, three indoor units 3, and one relay interposed between the outdoor unit 1 and the indoor unit 3. a unit 2; The relay unit 2 exchanges heat between the heat source side refrigerant and the heat medium. The outdoor unit 1 and the relay unit 2 are connected by a refrigerant pipe 5 that conducts the heat source side refrigerant. The relay unit 2 and the indoor unit 3a are connected by a heat medium branch pipe 6a that conducts the heat medium. The relay unit 2 and the indoor unit 3b are connected by a heat medium branch pipe 6b that conducts the heat medium. The relay unit 2 and the indoor unit 3c are connected by a heat medium branch pipe 6c that conducts the heat medium. Cold heat or heat generated in the outdoor unit 1 is delivered to the indoor unit 3 via the relay unit 2 .

The outdoor unit 1 is normally placed outdoors, such as on the roof of a building 9 such as a building, and supplies cold or hot heat to the indoor unit 3 via the relay unit 2 . The indoor unit 3 is arranged at a position capable of supplying cooling air or heating air to an indoor space 7 such as a living room inside the building 9, and supplies cooling air or heating air to the indoor space 7 to be air-conditioned. . The relay unit 2 is configured as a separate housing from the outdoor unit 1 and the indoor unit 3 so that it can be arranged at a position separate from the outdoor and indoor spaces 7 . The relay unit 2 is connected to the outdoor unit 1 by a refrigerant pipe 5 and is connected to the indoor unit 3 by a heat medium branch pipe 6 . The relay unit 2 transfers cold heat or heat supplied from the outdoor unit 1 to the indoor unit 3 .

The operation of the air conditioner 100 according to Embodiment 1 will be briefly described.

The heat source side refrigerant is conveyed from the outdoor unit 1 to the relay unit 2 through the refrigerant pipe 5 . The transported heat source side refrigerant exchanges heat with the heat medium in the heat medium heat exchanger 20 (see FIG. 2) in the relay unit 2 to heat or cool the heat medium. That is, the heat medium heat exchanger 20 produces hot water or cold water. Hot water or cold water produced by the relay unit 2 is conveyed to the indoor unit 3 . The hot water or cold water conveyed to the indoor unit 3 is used for heating or cooling the indoor space 7 in the indoor unit 3 .

As the heat source side refrigerant, for example, single refrigerants such as R-22, R-134a and R-32, pseudo-azeotropic refrigerant mixtures such as R-410A and R-404A, and non-azeotropic refrigerant mixtures such as R-407C are used. include. It also includes refrigerants and refrigerant mixtures that have a relatively low global warming potential, such as CF3CF=CH2, which contain double bonds in their chemical formulas. In addition, natural refrigerants such as _CO2 , propane, etc. can be used. As the heat medium, for example, water, an antifreeze solution, a mixed solution of water and an antifreeze solution, a mixed solution of an additive having a high anticorrosion effect and water, or the like can be used.

As shown in FIG. 1 , in the air conditioner 100 according to Embodiment 1, the outdoor unit 1 and the relay unit 2 are connected using two refrigerant pipes 5 . The relay unit 2 and each indoor unit 3 are connected using two heat medium branch pipes 6 . As described above, in the air conditioner 100 according to Embodiment 1, by connecting the outdoor unit 1, the indoor unit 3, and the relay unit 2 using the refrigerant pipe 5 and the heat medium branch pipe 6, construction is facilitated. there is

Note that FIG. 1 shows an example in which the relay unit 2 is arranged in a space 8 such as a ceiling space, which is inside the building 9 but different from the indoor space 7 . The relay unit 2 may be placed in any place other than behind the ceiling or in the indoor space 7 as long as it is ventilated with the outdoors in some way. It is also possible to place it in a well-ventilated place. Also, the relay unit 2 can be arranged near the outdoor unit 1 . However, it should be noted that if the distance from the relay unit 2 to the indoor unit 3 is too long, the power for transporting the heat medium will be considerably increased, and the energy saving effect will be reduced.

In FIG. 1, the case where the outdoor unit 1 is arranged outdoors is shown as an example, but it is not limited to this. For example, the outdoor unit 1 may be placed in a place surrounded by walls such as a machine room with a ventilation port. The outdoor unit 1 may be arranged inside the building 9 if waste heat can be discharged outside the building 9 through an exhaust duct. The outdoor unit 1 may be arranged inside the building 9 even when the water-cooled outdoor unit 1 is used. Even if the outdoor unit 1 is arranged in such a place, no particular problem occurs.

In FIG. 1, the case where the indoor unit 3 is a ceiling cassette type is shown as an example, but it is not limited to this. It is sufficient that the heating air or the cooling air can be blown out.

Furthermore, the number of connected outdoor units 1, indoor units 3, and relay units 2 is not limited to the number shown in FIG. You have to decide the number of units.

When a plurality of relay units 2 are connected to one outdoor unit 1, the plurality of relay units 2 can be scattered in a shared space in a building 9 such as a building or in a space such as the ceiling space. can be done. By doing so, the heat exchanger related to heat medium in each relay unit 2 can cover the air conditioning load. In addition, the indoor unit 3 can be arranged at a distance or height within the allowable transfer range of the heat medium transfer device in each relay unit 2, and can be arranged over the entire building 9 such as a building. Become.

FIG. 2 is a diagram showing the configuration of the air conditioner 100 according to Embodiment 1. As shown in FIG. Based on FIG. 2, the configuration of the equipment and the like included in the air conditioner 100 will be described.

The air conditioner 100 includes a heat source side refrigerant circulation circuit A that circulates a heat source side refrigerant, and a heat medium circulation circuit B that circulates a heat medium such as water that transfers and transfers heat. Then, air conditioning is performed by cooling, heating, or the like. The heat source side refrigerant circulation circuit A functions as a heat source side device that heats or cools the heat medium in the heat medium circulation circuit B.

As shown in FIG. 2, the air conditioner 100 has an outdoor unit 1, a relay unit 2 and an indoor unit 3. The outdoor unit 1, relay unit 2 and indoor unit 3 will be described below.

<Outdoor unit 1>
The outdoor unit 1 conveys heat by circulating the heat source side refrigerant in the heat source side refrigerant circulation circuit A, and in the heat medium heat exchanger 20 of the relay unit 2, a unit that exchanges heat between the heat source side refrigerant and the heat medium. is. The outdoor unit 1 has a compressor 10, a refrigerant flow switching device 11, a heat source side heat exchanger 12, an accumulator 13, and a heat source side blower 14 in a housing.

The compressor 10 draws in the heat source side refrigerant, compresses the heat source side refrigerant to a high temperature and high pressure state, and conveys it to the heat source side refrigerant circulation circuit A. For example, it is an inverter compressor whose capacity is controllable. Good to configure. The refrigerant flow switching device 11 controls the flow of the heat source side refrigerant in the heating operation mode, which is the heating only operation mode and the heating main operation mode, and the cooling operation mode, which is the cooling only operation mode and the cooling main operation mode. and the flow of the heat source side refrigerant at.

The heat source side heat exchanger 12 functions as an evaporator during heating operation and as a condenser during cooling operation, and performs heat exchange between a fluid such as air supplied from the heat source side blower 14 and the heat source side refrigerant. , evaporates or condenses the heat source side refrigerant. The accumulator 13 is provided on the suction side of the compressor 10 and stores excess refrigerant due to differences between heating operation and cooling operation, or excess refrigerant due to transient changes in operation.

The outdoor unit 1 further has a first connection pipe 15, a second connection pipe 16, a first backflow prevention device 17a, a first backflow prevention device 17b, a first backflow prevention device 17c, and a first backflow prevention device 17d. Here, check valves are used as the first backflow prevention devices 17a to 17d.

The first backflow prevention device 17a is provided in the refrigerant pipe 5 between the heat source side heat exchanger 12 and the relay unit 2, and allows the heat source side refrigerant to flow only in the direction from the outdoor unit 1 to the relay unit 2. The first backflow prevention device 17a is a device that prevents the high-temperature and high-pressure gas refrigerant from flowing back from the first connection pipe 15 to the heat source side heat exchanger 12 in the heating only operation mode and the heating main operation mode. be.

The first backflow prevention device 17b is provided in the second connection pipe 16, and circulates the heat source side refrigerant returned from the relay unit 2 to the suction side of the compressor 10 during heating operation. The first backflow prevention device 17b is a device that prevents the high-pressure liquid or gas-liquid two-phase refrigerant from flowing back from the first connection pipe 15 to the accumulator 13 during the cooling-only operation mode and the cooling-main operation mode. is.

The first backflow prevention device 17c is provided in the refrigerant pipe 5 between the relay unit 2 and the refrigerant flow switching device 11, and allows the heat source side refrigerant to flow only in the direction from the relay unit 2 to the outdoor unit 1. The first backflow prevention device 17c is a device that prevents the high-pressure liquid or gas-liquid two-phase refrigerant from flowing back from the second connection pipe 16 to the accumulator 13 in the cooling only operation mode and the cooling main operation mode. is.

The first backflow prevention device 17d is provided in the first connection pipe 15 and allows the heat source side refrigerant discharged from the compressor 10 to flow to the relay unit 2 during heating operation. The first backflow prevention device 17d prevents high-temperature and high-pressure gas refrigerant from flowing back from the flow path on the discharge side of the compressor 10 to the second connection pipe 16 during the heating-only operation mode and the heating-main operation mode. It is a device that

Thus, by providing the first connection pipe 15, the second connection pipe 16, and the first backflow prevention device 17a to the first backflow prevention device 17d, the flow into the relay unit 2 regardless of the operation requested by the indoor unit 3. It is possible to make the flow of the cooling medium to be unidirectional. Here, check valves are used as the first backflow prevention devices 17a to 17d, but any device that can prevent backflow of the refrigerant may be used. For example, as the first backflow prevention device 17a to the first backflow prevention device 17d, an opening/closing device, a throttle device having a fully closing function, or the like can be used.

In the outdoor unit 1, the first connection pipe 15 is the refrigerant pipe 5 between the refrigerant flow switching device 11 and the first backflow prevention device 17c, and the refrigerant pipe 5 between the first backflow prevention device 17a and the relay unit 2. and the pipe 5 are connected. In the outdoor unit 1, the second connection pipe 16 is the refrigerant pipe 5 between the first backflow prevention device 17c and the relay unit 2, and the refrigerant pipe 5 between the heat source side heat exchanger 12 and the first backflow prevention device 17a. and the pipe 5 are connected. 2, the first connection pipe 15, the second connection pipe 16, the first backflow prevention device 17a, the first backflow prevention device 17b, the first backflow prevention device 17c, and the first backflow prevention device 17d are provided. shown in the example. However, the present invention is not limited to these, and they do not necessarily have to be provided.

<Indoor unit 3>
An indoor heat exchanger 30a is mounted on the indoor unit 3a. An indoor heat exchanger 30b is mounted on the indoor unit 3b. An indoor heat exchanger 30c is mounted on the indoor unit 3c.

The indoor heat exchanger 30a is connected to the main heat medium pipe 4 via the heat medium branch pipe 6a_1. The indoor heat exchanger 30a is connected to the second heat medium flow switching device 26a by a heat medium branch pipe 6a_1. A temperature sensor 40a is provided in the indoor heat exchanger 30a. The temperature sensor 40a is provided in the indoor heat exchanger 30a, and measures the temperature of the air that flows into the indoor heat exchanger 30a and exchanges heat with the heat medium that flows through the indoor heat exchanger 30a. The temperature of the air measured by the temperature sensor 40a is also referred to as the intake temperature or the first temperature. Also, the indoor heat exchanger 30a is connected to the first heat medium flow switching device 25a by the heat medium branch pipe 6a_2 via the heat medium flow control device 27a provided in the heat medium branch pipe 6a_2. The indoor heat exchanger 30b is connected to the main heat medium pipe 4 via the heat medium branch pipe 6b_1. The indoor heat exchanger 30b is connected to the second heat medium flow switching device 26b by a heat medium branch pipe 6b_1. A temperature sensor 40b is provided in the indoor heat exchanger 30b. The temperature sensor 40b is provided in the indoor heat exchanger 30b, and measures the temperature of the air that flows into the indoor heat exchanger 30b and exchanges heat with the heat medium that flows through the indoor heat exchanger 30b. The temperature of the air measured by the temperature sensor 40b is also referred to as the intake temperature or the first temperature. Also, the indoor heat exchanger 30b is connected to the first heat medium flow switching device 25b by the heat medium branch pipe 6b_2 via the heat medium flow control device 27b provided in the heat medium branch pipe 6b_2. The indoor heat exchanger 30c is connected to the main heat medium pipe 4 via the heat medium branch pipe 6c_1. The indoor heat exchanger 30c is connected to the second heat medium flow switching device 26c by a heat medium branch pipe 6c_1. A temperature sensor 40c is provided in the indoor heat exchanger 30c. The temperature sensor 40c is provided in the indoor heat exchanger 30c and measures the intake temperature of the air flowing into the indoor heat exchanger 30c. Also, the indoor heat exchanger 30c is connected to the first heat medium flow switching device 25c by the heat medium branch pipe 6c_2 via the heat medium flow control device 27c provided in the heat medium branch pipe 6c_2.

The indoor heat exchangers 30a to 30c exchange heat between air supplied from a blower such as a fan (not shown) and a heat medium, and supply heating air or air to the indoor space 7. Generate cooling air.

Further, in the indoor unit 3, ducts (not shown) are attached to the indoor heat exchangers 30a to 30c. A blower (not shown) can be used to take outside air into the indoor space 7 through a duct for ventilation.

FIG. 2 shows an example in which three indoor units 3 are connected to the relay unit 2, which are shown as indoor unit 3a, indoor unit 3b, and indoor unit 3c from the top of the paper. As in FIG. 1, the number of connected indoor units 3 is not limited to three as shown in FIG.

<Relay unit 2>
The relay unit 2 has three heat medium heat exchangers 20 . Also, the heat source side refrigerant circulation circuit A of the relay unit 2 has three expansion devices 22 , two opening/closing devices 23 , and three refrigerant flow switching devices 24 . The heat medium circulation circuit B includes three pumps 21, three first heat medium flow switching devices 25, three second heat medium flow switching devices 26, and three heat medium flow rate adjusting devices 27. and two third heat medium flow switching devices 28 .

The three heat medium heat exchangers 20 exchange heat between the heat source side refrigerant and the heat medium. The three heat medium heat exchangers 20 function as condensers (radiators) or evaporators. The heat medium heat exchanger 20 has a first heat medium heat exchanger 20a, a second heat medium heat exchanger 20b and a third heat medium heat exchanger 20c.

The first heat medium heat exchanger 20a is provided between the expansion device 22a and the refrigerant flow switching device 24a in the heat source side refrigerant circulation circuit A, and heat exchange for cooling the heat medium in the cooling/heating mixed operation mode. Become a vessel. The second heat medium heat exchanger 20b is provided between the throttle device 22b and the refrigerant flow switching device 24b in the heat source side refrigerant circulation circuit A, and heat that heats the heat medium is provided during the cooling and heating mixed operation mode. become an exchanger. The third heat medium heat exchanger 20c is provided between the expansion device 22c and the refrigerant flow switching device 24c in the heat source side refrigerant circulation circuit A, detects the load or capacity of the indoor unit 3, and is a heat exchanger that cools or heats and regulates the load.

The three expansion devices 22 function as pressure reducing valves and expansion valves, and reduce the pressure of the heat source side refrigerant to expand it. The diaphragm device 22 has a diaphragm device 22a, a diaphragm device 22b, and a diaphragm device 22c.

The throttle device 22a is connected to the first heat medium heat exchanger 20a and provided upstream of the first heat medium heat exchanger 20a in the flow of the heat source side refrigerant during the cooling only operation mode. The expansion device 22b is connected to the second heat medium heat exchanger 20b and provided upstream of the second heat medium heat exchanger 20b in the flow of the heat source side refrigerant in the cooling only operation mode. The expansion device 22c is connected to the third heat medium heat exchanger 20c and provided upstream of the third heat medium heat exchanger 20c in the flow of the heat source side refrigerant in the cooling only operation mode. The three expansion devices 22 are composed of, for example, electronic expansion valves whose opening can be controlled.

The two opening/closing devices 23 are composed of two-way valves or the like, and open/close the refrigerant pipes 5 . The switchgear 23 has a switchgear 23a and a switchgear 23b. The opening/closing device 23a is provided in the refrigerant pipe 5a on the inlet side of the heat source side refrigerant. The opening/closing device 23b is connected to the refrigerant pipe 5b that connects the outlet side of the heat source side refrigerant. The opening/closing device 23 may be an electronic expansion valve such as a throttle device.

The three refrigerant flow switching devices 24 are composed of four-way valves, etc., and switch the flow of the heat source side refrigerant according to the operation mode. The refrigerant flow switching device 24 has a refrigerant flow switching device 24a, a refrigerant flow switching device 24b, and a refrigerant flow switching device 24c.

The refrigerant flow switching device 24a is provided downstream of the first heat medium heat exchanger 20a in the flow of the heat source side refrigerant during the cooling only operation mode. The refrigerant flow switching device 24b is provided downstream of the second heat medium heat exchanger 20b in the flow of the heat source side refrigerant during the cooling only operation mode. The refrigerant flow switching device 24c is provided downstream of the third heat medium heat exchanger 20c in the flow of the heat source side refrigerant during the cooling only operation mode. In addition, in the cooling/heating mixed operation mode, the refrigerant flow switching device 24c detects the load or capacity of the indoor unit and switches to a circuit for operation on the insufficient capacity side.

Next, the heat medium circulation circuit B in the relay unit 2 will be explained.

The three pumps 21 pressurize the heat medium passing through the heat medium main pipe 4 to circulate the heat medium circulation circuit B. The pump 21 has a pump 21a, a pump 21b and a pump 21c.

The pump 21a is upstream of the first heat medium heat exchanger 20a, and between the first heat medium heat exchanger 20a and the first heat medium flow switching device 25 and the third heat medium flow switching device 28a. It is provided in the heat medium main pipe 4 in . The pump 21b is provided in the heat medium main pipe 4 between the second heat medium heat exchanger 20b and the first heat medium flow switching device 25 and the third heat medium flow switching device 28b. The pump 21c is provided in the main heat medium pipe 4 between the third heat medium heat exchanger 20 and the third heat medium flow switching device 28a.

The frequency of the pump 21c is controlled according to the heat load. When the load can be supplemented by the first heat medium heat exchanger 20a and the second heat medium heat exchanger 20b, the pump 21c is stopped and the heat medium is not allowed to flow through the third heat medium heat exchanger 20c.

The first heat medium flow switching device 25 is composed of a three-way valve or the like, and switches the heat medium flow path. The first heat medium flow switching device 25 includes a first heat medium flow switching device 25a, a first heat medium flow switching device 25b, and a first heat medium flow switching device 25c.

The number of first heat medium flow switching devices 25 is provided according to the number of indoor units 3 arranged, and in FIG. 2, three units are provided. The first heat medium flow switching device 25 is provided in the heat medium main pipe 4 on the outlet side of the heat medium flow path in the indoor heat exchanger 30 . One of the three flow paths of the first heat medium flow switching device 25 is connected to the first heat medium heat exchanger 20a. Another one is connected to the second heat medium heat exchanger 20b. Another one is connected to the heat medium flow control device 27 . Further, switching of the heat medium flow paths by the first heat medium flow switching device 25 includes not only complete switching from one to the other but also partial switching from one to the other.

The second heat medium flow switching device 26 is composed of a three-way valve or the like, and switches the heat medium flow path. The second heat medium flow switching device 26 has a second heat medium flow switching device 26a, a second heat medium flow switching device 26b, and a second heat medium flow switching device 26c.

The number of the second heat medium flow switching devices 26 is provided according to the number of the indoor units 3 arranged, and in FIG. 2, three units are provided. The second heat medium flow switching device 26 is provided on the inlet side of the heat medium flow path in the indoor heat exchanger 30 . One of the three flow paths of the second heat medium flow switching device 26 is connected to the first heat medium heat exchanger 20a. Another one is connected to the second heat medium heat exchanger 20b. Another one is connected to the indoor heat exchanger 30 . In addition, the switching of the heat medium flow paths by the second heat medium flow switching device 26 includes not only complete switching from one to the other but also partial switching from one to the other.

The heat medium flow rate adjusting device 27 is a device that adjusts the flow rate of the heat medium flowing through the indoor unit 3 . The heat medium flow control device 27 has a heat medium flow control device 27a, a heat medium flow control device 27b, and a heat medium flow control device 27c.

The heat medium flow rate adjusting device 27 is composed of a two-way valve or the like that can control the opening area, and controls the flow rate flowing through the heat medium branch pipes 6 . The number of heat medium flow control devices 27 is provided according to the number of indoor units 3 to be arranged. One end of the heat medium flow control device 27 is connected to the indoor heat exchanger 30 . The other is connected to the first heat medium flow switching device 25 . Here, the heat medium flow control device 27 is provided on the outlet side of the heat medium flow path in the indoor heat exchanger 30 . However, the heat medium flow control device 27 may be provided on the inlet side of the heat medium flow path of the indoor heat exchanger 30 . Further, in the indoor unit 3, when the load such as stoppage and thermo-OFF is not required, the heat medium supply to the indoor unit 3 can be stopped by fully closing the heat medium flow control device 27. This also applies to other operation modes described below.

If the first heat medium flow switching device 25 or the second heat medium flow switching device 26 is added with the function of the heat medium flow rate adjusting device 27, the heat medium flow rate adjusting device 27 may be omitted. It is possible.

The third heat medium flow switching device 28 is composed of a three-way valve or the like, and switches the heat medium flow in the heat medium circulation circuit B according to the load during the cooling/heating mixed operation mode. The third heat medium flow switching device 28 has a third heat medium flow switching device 28a and a third heat medium flow switching device 28b.

The third heat medium flow switching device 28a is provided on the upstream side of the pump 21c and connected to the upstream sides of the pumps 21a and 21b. The third heat medium flow switching device 28a flows the heat medium flowing into the pump 21a or the heat medium flowing into the pump 21b to the third heat medium heat exchanger 20c via the pump 21c. Further, the third heat medium flow switching device 28b is provided downstream of the third heat medium heat exchanger 20c, and downstream of the first heat medium heat exchanger 20a and the second heat medium heat exchanger 20b. is connected with The third heat medium flow switching device 28b flows the heat medium output from the third heat medium heat exchanger 20c to the output side of the first heat medium heat exchanger 20a or the output side of the second heat medium heat exchanger 20b. .

In the cooling/heating mixed operation mode, when the cooling load of the indoor unit 3 is greater than the heating load, the third heat medium flow switching device 28a and the third heat medium flow switching device 28b are switched to the cooling side, and the first heat The medium heat exchanger 20a and the third heat medium heat exchanger 20c are arranged in parallel. On the other hand, when the cooling load of the indoor unit 3 is equal to or less than the heating load, the third heat medium flow switching device 28a and the third heat medium flow switching device 28a are switched to the heating side, and the second heat medium heat exchanger 20b and 3rd heat-medium heat exchanger 20c becomes parallel.

In addition, in the relay unit 2, the heat medium heat exchanger 20, the pump 21, the expansion device 22, the refrigerant flow switching device 24, and the third heat medium flow switching device 28 may be three or more.

The control device 50 centrally controls the operation of the air conditioner 100 . The control device 50 performs the following control in addition to the processing according to the first embodiment. The driving frequency of the compressor 10, the rotation speed of the heat source side blower 14, the switching of the refrigerant flow switching device 11, the driving frequency of the pump 21, the opening degree of the expansion device 22, the opening and closing of the opening and closing device 23, and the switching of the refrigerant flow switching device 24. This is control of switching of the refrigerant flow path. Also, switching of the refrigerant flow path of the first heat medium flow switching device 25, switching of the refrigerant flow path of the second heat medium flow switching device 26, adjustment of the heat medium flow rate of the heat medium flow control device 27, and adjustment of the heat medium flow rate of the heat medium flow control device 27. This is control of switching of the refrigerant flow path of the medium flow switching device 28 .

Although the control device 50 is mounted separately from the outdoor unit 1, the indoor unit 3, and the relay unit 2, it is not limited to this. It may be mounted on at least one of the relay units 2 . Also, it may be mounted on each of the outdoor unit 1, the indoor unit 3 and the relay unit 2 so as to be communicable.

When the processing circuit of the control device 50 is dedicated hardware, the processing circuit is, for example, a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. is applicable. Each functional unit implemented by the processing circuit may be implemented by separate hardware, or each functional unit may be implemented by one piece of hardware. When the processing circuit of the control device 50 is a CPU, each function executed by the processing circuit is implemented by software, firmware, or a combination of software and firmware. Software and firmware are written as programs and stored in the storage unit of the control device 50 . The CPU implements each function of the processing circuit by reading and executing the program stored in the storage unit. A part of the functions of the processing circuit may be realized by dedicated hardware, and a part thereof may be realized by software or firmware.

The heat medium main pipes 4 that conduct the heat medium are connected to the first heat medium heat exchanger 20a, connected to the second heat medium heat exchanger 20b, and connected to the third heat medium heat exchanger 20c. connected to the The heat medium main pipe 4 is branched according to the number of indoor units 3 connected to the relay unit 2 (here, three branches each). The heat medium main pipe 4 is connected to the first heat medium flow switching device 25 and the second heat medium flow switching device 26 . By controlling the first heat medium flow switching device 25 and the second heat medium flow switching device 26, the heat medium from the first heat medium heat exchanger 20a to the third heat medium heat exchanger 20c is subjected to indoor heat exchange. determines whether to flow into the vessel 30.

In the air conditioner 100, the compressor 10, the refrigerant flow switching device 11, the heat source side heat exchanger 12, the switching device 23, the refrigerant flow switching device 24, the heat medium heat exchanger 20, the expansion device 22, and the accumulator 13, A heat source side refrigerant circulation circuit A is configured by connecting with a refrigerant pipe 5 .

Also, the heat medium heat exchanger 20, the pump 21, the first heat medium flow switching device 25, the heat medium flow rate adjusting device 27, the indoor heat exchanger 30, the second heat medium flow switching device 26, and the third heat medium flow A heat medium circulation circuit B is configured by connecting the path switching device 28 with the heat medium main pipe 4 . That is, a plurality of indoor heat exchangers 30 are connected in parallel to each of the heat medium heat exchangers 20, and the heat medium circulation circuit B is configured as a plurality of systems.

In the air conditioner 100, the heat source side refrigerant circulating in the heat source side refrigerant circulation circuit A in the first heat medium heat exchanger 20a, the second heat medium heat exchanger 20b, and the third heat medium heat exchanger 20c and the heat medium circulation circuit A heat medium circulating through B exchanges heat. By using such a configuration, the air conditioner 100 can realize the optimum cooling operation or heating operation according to the indoor load.

<Driving mode>
Each operation mode executed by the air conditioner 100 will be described. This air conditioner 100 is capable of cooling operation or heating operation in each indoor unit 3 based on instructions from each indoor unit 3 . In other words, the air conditioner 100 can operate all of the indoor units 3 in the same manner, and can operate differently in each of the indoor units 3 .

The operation modes executed by the air conditioner 100 include a heating only operation mode, a cooling only operation mode, and a cooling/heating mixed operation mode. In the heating only operation mode, all of the indoor units 3 that are being driven perform the heating operation. In the cooling only operation mode, all of the indoor units 3 that are being driven perform the cooling operation.

The cooling/heating mixed operation mode includes a cooling main operation mode and a heating main operation mode. In the cooling main operation mode, the cooling load is larger than the heating load. In the heating-dominant operation mode, the cooling load is equal to or less than the heating load. Each operation mode will be described below together with the flow of the heat source side refrigerant and the heat medium.
<Cooling only operation mode>
FIG. 3 is a circuit diagram showing the flow of refrigerant and heat medium during cooling only operation of the air conditioner 100 according to Embodiment 1. As shown in FIG. In FIG. 3, the cooling only operation mode will be described by taking as an example the case where the cooling load is generated in all of the indoor heat exchangers 30a to 30c. In FIG. 3 , solid line arrows indicate the flow direction of the heat source side refrigerant, and broken line arrows indicate the flow direction of the heat medium.

In the case of the cooling only operation mode, the outdoor unit 1 switches the refrigerant flow switching device 11 so that the heat source side refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12 .

In the relay unit 2, the pumps 21a, 21b, and 21c are driven, and the heat medium flow control devices 27a to 27c are opened. Further, the heat medium circulates between each of the first heat medium heat exchanger 20a, the second heat medium heat exchanger 20b, and the third heat medium heat exchanger 20c and the indoor heat exchangers 30a to 30c. do. The refrigerant flow switching device 24a, the refrigerant flow switching device 24b, and the refrigerant flow switching device 24c are switched to the cooling side, the switching device 23a is open, and the switching device 23b is closed.

Also, the state of each port of the first heat medium flow switching device 25, the second heat medium flow switching device 26, and the third heat medium flow switching device 28 is switched to the cooling side. Here, switching to the cooling side means that, in FIG. Heating side. As for the third heat medium flow switching device 28, the lower port is for the cooling side, and the upper port is for the heating side.

First, the flow of the heat source side refrigerant in the heat source side refrigerant circulation circuit A will be described.

During the cooling only operation mode, the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12 via the refrigerant flow switching device 11 . The high-temperature and high-pressure gas refrigerant that has flowed into the heat source side heat exchanger 12 radiates heat to the surrounding air, condenses and liquefies to become a high-pressure liquid refrigerant. The high-pressure liquid refrigerant flows out of the outdoor unit 1 through the first backflow prevention device 17a. Then, the high-pressure liquid refrigerant flows into the relay unit 2 through the refrigerant pipe 5a.

The refrigerant that has flowed into the relay unit 2 passes through the opening/closing device 23a and is branched to the expansion device 22a, the expansion device 22b, and the expansion device 22c. The branched refrigerant expands in the expansion device 22a, the expansion device 22b, and the expansion device 22c to become a low-temperature, low-pressure two-phase refrigerant.

The low-temperature, low-pressure two-phase refrigerant expanded by the expansion device 22a flows into the first heat medium heat exchanger 20a that functions as an evaporator. The low-temperature, low-pressure two-phase refrigerant expanded by the expansion device 22b flows into the second heat medium heat exchanger 20b acting as an evaporator. The low-temperature, low-pressure two-phase refrigerant expanded by the expansion device 22c flows into the third heat medium heat exchanger 20c acting as an evaporator.

The low-temperature, low-pressure two-phase refrigerant that has flowed into the first heat medium heat exchanger 20a to the third heat medium heat exchanger 20c absorbs heat from the heat medium circulating in the heat medium circulation circuit B, and becomes a low-temperature, low-pressure gas refrigerant. The gas refrigerant in the first heat medium heat exchanger 20a flows out from the relay unit 2 via the refrigerant flow switching device 24a. The gas refrigerant in the second heat medium heat exchanger 20b flows out from the relay unit 2 via the refrigerant flow switching device 24b. The gas refrigerant in the third heat medium heat exchanger 20c flows out from the relay unit 2 via the refrigerant flow switching device 24c.

Then, the gas refrigerant flows into the outdoor unit 1 again through the refrigerant pipe 5b. The refrigerant that has flowed into the outdoor unit 1 passes through the first backflow prevention device 17 c and is sucked into the compressor 10 again via the refrigerant flow switching device 11 and the accumulator 13 .

Next, the flow of the heat medium in the heat medium circulation circuit B will be explained.

In the cooling only operation mode, cold heat of the heat source side refrigerant is transferred to the heat medium in the first heat medium heat exchanger 20a to the third heat medium heat exchanger 20c, and the cooled heat medium is pressurized by the pump 21 and flows out. do. The outflowing heat medium flows through the heat medium main pipe 4 and the heat medium branch pipe 6, passes through the second heat medium flow switching device 26a to the second heat medium flow switching device 26c, and enters the indoor heat exchanger 30a. ~ flows into the indoor heat exchanger 30c. Then, the indoor space 7 is cooled by the heat medium absorbing heat from the indoor air in the indoor heat exchangers 30a to 30c.

Then, the heat medium flows out from the indoor heat exchangers 30a to 30c and flows into the heat medium flow rate adjusting devices 27a to 27c. At this time, due to the action of the heat medium flow rate adjusting devices 27a to 27c, the flow rate of the heat medium is controlled to the flow rate necessary to cover the air conditioning load required in the room other than the indoor heat exchangers 30a to 30c. It flows into the indoor heat exchanger 30c. The heat medium flowing out from the heat medium flow rate adjusting device 27a to the heat medium flow rate adjusting device 27c passes through the first heat medium flow switching device 25a to the first heat medium flow switching device 25c and then through the pumps 21a to 21c. and flows into the first heat medium heat exchanger 20a to the third heat medium heat exchanger 20c. In the first to third heat medium heat exchangers 20a to 20c, the amount of heat absorbed from the indoor space 7 through the indoor unit 3 is transferred to the refrigerant side.

The heat medium flow control devices 27a to 27c corresponding to the indoor heat exchangers 30a to 30c with no heat load are fully closed. In addition, the heat medium flow control devices 27a to 27c corresponding to the indoor heat exchangers 30a to 30c having a heat load adjust the opening degrees, and the indoor heat exchangers 30a to 30c Adjust the heat load at 30c.

At this time, the first heat medium flow switching device 25 and the second heat medium flow switching device 26 are arranged so that the flow paths from the first heat medium heat exchanger 20a to the third heat medium heat exchanger 20c are secured. , the opening is controlled to an intermediate degree. Alternatively, the first heat medium flow switching device 25 and the second heat medium flow switching device 26 are opened according to the heat medium temperature at the outlets of the first heat medium heat exchanger 20a to the third heat medium heat exchanger 20c. controlled to a degree.

<All heating operation mode>
FIG. 4 is a circuit diagram showing the flow of refrigerant and heat medium during full-warm operation of the air-conditioning apparatus 100 according to Embodiment 1. As shown in FIG. In FIG. 4, the heating only operation mode will be described by taking as an example a case where a thermal load is generated in all of the indoor heat exchangers 30a to 30c. In FIG. 4 , solid line arrows indicate the flow direction of the heat source side refrigerant, and broken line arrows indicate the flow direction of the heat medium.

In the case of the heating only operation mode shown in FIG. Switch to flow.

In the relay unit 2, the pumps 21a, 21b, and 21c are driven, and the heat medium flow control devices 27a to 27c are opened. This allows the heat medium to circulate between each of the first to third heat medium heat exchangers 20a to 20c and the indoor heat exchangers 30a to 30c. Further, the refrigerant flow switching device 24a, the refrigerant flow switching device 24b, and the refrigerant flow switching device 24c are switched to the heating side, the switching device 23a is closed, and the switching device 23b is open.

Also, the first heat medium flow switching device 25, the second heat medium flow switching device 26, and the third heat medium flow switching device 28 are switched to the heating side. Here, switching to the heating side means that, in FIG. Cooling side. As for the third heat medium flow switching device 28, the upper port is for the heating side, and the lower port is for the cooling side.

First, the flow of the heat source side refrigerant in the heat source side refrigerant circulation circuit A will be described.

In the full-warm operation mode, the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 passes through the first connection pipe 15 and the first backflow prevention device 17d via the refrigerant flow switching device 11, and flows out of the outdoor unit 1. do. Then, it flows into the relay unit 2 through the refrigerant pipe 5a.

The refrigerant flowing into the relay unit 2 passes through the refrigerant flow switching device 24a, the refrigerant flow switching device 24b, and the refrigerant flow switching device 24c to the first heat medium heat exchanger 20a and the second heat medium heat exchanger. 20b and the third heat medium heat exchanger 20c. The refrigerant that has flowed into the first heat medium heat exchanger 20a, the second heat medium heat exchanger 20b, and the third heat medium heat exchanger 20c radiates heat to the heat medium circulating in the heat medium circulation circuit B, resulting in a high-pressure liquid refrigerant. becomes. The high-pressure liquid refrigerant expands in the expansion devices 22a, 22b, and 22c to become a low-temperature, low-pressure two-phase refrigerant, and flows out of the relay unit 2 through the opening/closing device 23b. Then, it flows into the outdoor unit 1 again through the refrigerant pipe 5 .

The refrigerant that has flowed into the outdoor unit 1 passes through the second connection pipe 16 and the first backflow prevention device 17b, flows into the heat source side heat exchanger 12 acting as an evaporator, absorbs heat from the surrounding air, and becomes a low-temperature low-pressure refrigerant. It becomes a gas refrigerant. The gas refrigerant is sucked into the compressor 10 again through the refrigerant flow switching device 11 and the accumulator 13 .

Note that the operation of the heat medium in the heat medium circulation circuit B is the same as in the cooling only operation mode. In the heating only operation mode, the heat medium is heated by the refrigerant in the first heat medium heat exchanger 20a to the third heat medium heat exchanger 20c, and heat is released to the indoor air in the indoor heat exchangers 30a to 30c. to heat the air-conditioned space.

<Cooling main operation mode (cooling/heating mixed operation mode)>
FIG. 5 is a circuit diagram showing the flow of refrigerant in the cooling main operation mode of the air conditioner 100 according to Embodiment 1. As shown in FIG. In FIG. 5, the cooling main operation mode in the cooling/heating mixed operation mode when the cold load and the thermal load are generated in the indoor heat exchangers 30a to 30c and the cold load is larger than the thermal load will be described. In FIG. 5 , solid line arrows indicate the flow direction of the heat source side refrigerant, and broken line arrows indicate the flow direction of the heat medium.

During the cooling main operation mode, the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12 via the refrigerant flow switching device 11 . The gas refrigerant that has flowed into the heat source side heat exchanger 12 radiates heat to the surrounding air, condenses, becomes a two-phase refrigerant, and flows out of the outdoor unit 1 through the first backflow prevention device 17a. Then, the two-phase refrigerant flowing out of the outdoor unit 1 flows into the relay unit 2 through the refrigerant pipe 5a.

The refrigerant that has flowed into the relay unit 2 passes through the refrigerant flow switching device 24b and flows into the second heat medium heat exchanger 20b acting as a condenser. liquid refrigerant.

The high-pressure liquid refrigerant is expanded by the expansion device 22b to become a low-temperature, low-pressure two-phase refrigerant. The two-phase refrigerant flows through the throttle device 22a into the first heat medium heat exchanger 20a acting as an evaporator. The refrigerant that has flowed into the first heat medium heat exchanger 20a absorbs heat from the heat medium circulating in the heat medium circulation circuit B, becomes a low-pressure gas refrigerant, and flows out of the relay unit 2 via the refrigerant flow switching device 24a.

However, it is determined whether to heat or cool the heat medium that exchanges heat with the heat source side refrigerant in the third heat medium heat exchanger 20c by switching the refrigerant flow switching device 24c according to the heat load situation. FIG. 5 shows a case where the third heat medium heat exchanger 20c acts as an evaporator and the refrigerant flow switching device 24c is switched to the cooling side. In this case, the two-phase refrigerant flows through the throttle device 22c into the third heat medium heat exchanger 20c acting as an evaporator. The refrigerant flowing into the third heat medium heat exchanger 20c absorbs heat from the heat medium circulating in the heat medium circulation circuit B, becomes a low-pressure gas refrigerant, and flows out of the relay unit 2 via the refrigerant flow switching device 24c.

Then, the refrigerant that has flowed out of the relay unit 2 flows into the outdoor unit 1 again through the refrigerant pipe 5b. The refrigerant that has flowed into the outdoor unit 1 passes through the first backflow prevention device 17 c and is sucked into the compressor 10 again via the refrigerant flow switching device 11 and the accumulator 13 .

In the heat medium circulation circuit B, the heat of the refrigerant is transferred to the heat medium in the second heat medium heat exchanger 20b. Then, the heated heat medium flows through the main heat medium pipe 4 and the heat medium branch pipe 6 by the pump 21b. The first heat medium flow switching device 25a to the first heat medium flow switching device 25c and the second heat medium flow switching device 26a to the second heat medium flow switching device 26c are controlled, and indoor heat exchange with a heating request The heat medium flowing into the unit 30a to the indoor heat exchanger 30c is radiated to the indoor air. The indoor air is heated to heat the air-conditioned space.

On the other hand, cold heat of the refrigerant is transferred to the heat medium in the first heat medium heat exchanger 20a and the third heat medium heat exchanger 20c. The cooled heat medium flows through the heat medium main pipe 4 and the heat medium branch pipe 6 by the pumps 21a and 21c. The heat medium heat-exchanged in the third heat medium heat exchanger 20c is switched by the third heat medium flow switching device 28a and the third heat medium flow switching device 28 corresponding to the switching of the refrigerant flow switching device 24c. be done. In the case of the cooling main operation mode, the third heat medium flow switching device 28a and the third heat medium flow switching device 28 are switched to the cooling side. In switching to the cooling side, the third heat medium flow switching device 28a opens the valve leading to the heat medium main pipe 4 connected to the upstream side of the pump 21a, and opens the heat medium main pipe upstream of the pump 21b. Close the valve leading to 4. The third heat medium flow switching device 28b opens the valve leading to the heat medium main pipe 4 connected to the output side of the first heat medium heat exchanger 20a, and the output side of the second heat medium heat exchanger 20b. A valve leading to the connected main heat medium pipe 4 is closed.

The first heat medium flow switching device 25a to the first heat medium flow switching device 25c and the second heat medium flow switching device 26a to the second heat medium flow switching device 26c are controlled, and indoor heat exchange with cooling demand The heat medium that has flowed into the unit 30a to the indoor heat exchanger 30c absorbs heat from the indoor air. The indoor air is cooled to cool the air-conditioned space.

The heat medium flow control devices 27a to 27c corresponding to the indoor heat exchangers 30a to 30c with no heat load are fully closed. In addition, the heat medium flow rate adjusting devices 27a to 27c corresponding to the indoor heat exchangers 30a to 30c having a heat load adjust the opening degrees, and the heat loads at the indoor heat exchangers 30a to 30c are adjusted. adjust the

<Heating main operation mode (cooling/heating mixed operation mode)>
FIG. 6 is a circuit diagram showing the flow of refrigerant in the heating main operation mode of the air conditioner 100 according to Embodiment 1. As shown in FIG. In FIG. 6, a cooling load and a thermal load are generated in the indoor heat exchangers 30a to 30c, and the cooling load is less than the thermal load. In FIG. 6 , solid line arrows indicate the flow direction of the heat source side refrigerant, and broken line arrows indicate the flow direction of the heat medium.

During heating-main operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 passes through the refrigerant flow switching device 11, the first connection pipe 15, and the first backflow prevention device 17b, and then from the outdoor unit 1. leak. The high-temperature and high-pressure gas refrigerant flowing out of the outdoor unit 1 flows into the relay unit 2 through the refrigerant pipe 5a.

The refrigerant that has flowed into the relay unit 2 passes through the refrigerant flow switching device 24b and flows into the second heat medium heat exchanger 20b acting as a condenser. liquid refrigerant.

The high-pressure liquid refrigerant is expanded by the expansion device 22b to become a low-temperature, low-pressure two-phase refrigerant. The two-phase refrigerant flows through the throttle device 22a into the first heat medium heat exchanger 20a acting as an evaporator. The refrigerant flowing into the first heat medium heat exchanger 20a absorbs heat from the heat medium circulating in the heat medium circulation circuit B, and flows out of the relay unit 2 via the refrigerant flow switching device 24a.

However, it is determined whether to heat or cool the heat medium that exchanges heat with the heat source side refrigerant in the third heat medium heat exchanger 20c by switching the refrigerant flow switching device 24c according to the heat load situation. FIG. 6 shows a case where the third heat medium heat exchanger 20c acts as a condenser and the refrigerant flow switching device 24c is switched to the heating side. In this case, the high-temperature and high-pressure gas refrigerant flows through the refrigerant flow switching device 24c into the third heat medium heat exchanger 20c acting as a condenser. The refrigerant that has flowed into the third heat medium heat exchanger 20c radiates heat to the heat medium circulating in the heat medium circulation circuit B and becomes a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is expanded by the expansion device 22c to become a low-temperature, low-pressure two-phase refrigerant. The two-phase refrigerant flows through the throttle device 22a into the first heat medium heat exchanger 20a acting as an evaporator. The refrigerant flowing into the first heat medium heat exchanger 20a absorbs heat from the heat medium circulating in the heat medium circulation circuit B, and flows out of the relay unit 2 via the refrigerant flow switching device 24a.

Then, the refrigerant that has flowed out of the relay unit 2 flows into the outdoor unit 1 again through the refrigerant pipe 5b. The refrigerant that has flowed into the outdoor unit 1 passes through the second connection pipe 16 and the first backflow prevention device 17b, flows into the heat source side heat exchanger 12 acting as an evaporator, absorbs heat from the surrounding air, and cools down to low temperature and low pressure. gas refrigerant. The gas refrigerant is sucked into the compressor 10 again through the refrigerant flow switching device 11 and the accumulator 13 .

Note that the operation of the heat medium in the heat medium circulation circuit B, the operation of the pump 21, the first heat medium flow switching device 25, the second heat medium flow switching device 26, the heat medium flow control device 27, and the indoor heat exchanger 30 is the same as the cooling main operation mode. Regarding the third heat medium flow switching device 28a and the third heat medium flow switching device 28b, contrary to the cooling main operation mode, the second heat medium heat exchanger 20b side is opened, and the first heat medium heat exchanger is opened. 20a side is closed.

FIG. 7 is a diagram showing a flowchart for determining whether the third heat medium heat exchanger 20c is used for heating or cooling in the cooling/heating operation mode of the air conditioner 100 according to Embodiment 1.

In the cooling/heating mixed operation mode, the control device 50 controls the cooling load of the plurality of indoor units 3 and 3 is obtained (step S1). Here, the cooling load and heating load are capacities determined by the rating of the indoor unit 3 . The cooling load and heating load may be obtained by comparing the temperature of the heat medium flowing out of the indoor unit 3 and the target temperature instead of the intake temperature.

Next, it is determined whether the obtained cooling load is greater than the obtained heating load (step S2). If the cooling load is greater than the calculated heating load (YES in step S2), the third heat medium heat exchanger 20c is used for cooling. Specifically, the control device 50 switches the refrigerant flow switching device 24b, the third heat medium flow switching device 28a, and the third heat medium flow switching device 28b to the cooling side (step S3). On the other hand, if the cooling load is less than or equal to the heating load (NO in step S2), the third heat medium heat exchanger 20c is used for heating. Specifically, the control device 50 switches the refrigerant flow switching device 24b, the third heat medium flow switching device 28a, and the third heat medium flow switching device 28b to the heating side (step S4).

After step S3 or step S4, the pump 21 is driven (step S5).

Next, it is determined whether the detection time has elapsed since the cooling/heating operation mode was started (step S6). If it is the detection time (YES in step S6), the difference between the suction temperature and the target temperature of the indoor unit 3 is the largest in accordance with the operation mode of the indoor unit 3, and the third heat medium heat exchanger 20c is turned on. It is used for cooling or heating (step S7). After that, the process returns to the process of step S1. If it is not the detection time (NO in step S6), the determination in step S6 as to whether it is the detection time is continued.

(Modification)
FIG. 8 is a flowchart of a modified example for determining whether to use the third heat medium heat exchanger 20c for heating or cooling in the cooling/heating operation mode of the air conditioner 100 according to Embodiment 1. FIG. In FIG. 8, the description of steps that are the same as those in FIG. 7 will be omitted, and the different step S7_1 will be described here.

In step S7_1, the first temperature difference, which is the difference in the first detection time between the suction temperature measured by the temperature sensor 40 and the target temperature of the indoor unit 3, the suction temperature measured by the temperature sensor 40, and the indoor unit 3 In accordance with the operation mode of the indoor unit 3 among the plurality of indoor units 3 having the smallest difference from the second temperature difference, which is the difference at the second detection time after the first detection time, from the target temperature of 3 The heat medium heat exchanger 20c is used for cooling or heating. After that, the process returns to the process of step S1. As the operation time of the air conditioner 100 elapses, the intake temperature of each indoor unit 3 approaches the target temperature. Therefore, in the indoor unit 3 with sufficient cooling capacity or heating capacity, the second temperature difference at the second detection time after the first detection time is a small value with respect to the first temperature difference at the first detection time, and the first temperature difference and the second temperature difference increases. On the other hand, the difference between the first temperature difference and the second temperature difference is small in the indoor unit 3 with insufficient cooling capacity or heating capacity. Therefore, in step S7_2, the third heat medium heat exchanger is operated in accordance with the operation mode of the indoor unit 3 in which the difference between the first temperature difference and the second temperature difference is the smallest, that is, the cooling capacity or the heating capacity is insufficient. 20c has been determined.

(Modification 2)
The processing of step S7 in FIG. 7 and the processing of step S7_1 in FIG. 8 may be combined.

FIG. 9 is a flowchart of modification 2 for determining whether the third heat medium heat exchanger 20c is used for heating or cooling in the cooling/heating operation mode of the air conditioner 100 according to the first embodiment. In FIG. 9, the description of steps that are the same as those in FIGS. 7 and 8 will be omitted, and the different step S7_2 will be described here.

As shown in FIG. 9, the third heat medium heat exchanger 20c is used for cooling or heating according to the operation mode of the indoor unit 3 in which the difference between the suction temperature and the target temperature of the indoor unit 3 is the largest. (step S7).

Next, it is determined whether the time condition is satisfied or whether the temperature difference between the target temperature and the intake temperature of the temperature sensor 40 is equal to or less than a specific threshold (step S7_2). If it is determined in step S7_2 that the time condition is not satisfied, or if it is determined that the temperature difference between the target temperature and the intake temperature of the temperature sensor 40 is not equal to or less than a specific threshold (NO in step S7_2), step S1 return to the process of

On the other hand, if it is determined in step S7_2 that the time condition is satisfied or if the temperature difference between the target temperature and the intake temperature of the temperature sensor 40 is determined to be greater than a specific threshold (YES in step S7_2), the temperature is determined to be higher than the specified threshold. After the difference in the first detection time between the suction temperature measured by the sensor 40 and the target temperature of the indoor unit 3 and the first detection time between the suction temperature measured by the temperature sensor 40 and the target temperature of the indoor unit 3 The third heat medium heat exchanger 20c is used for cooling or heating in accordance with the operation mode of the indoor unit 3 among the plurality of indoor units 3 whose difference from the difference in the second detection time is the smallest ( Step S7_1). After that, the process returns to the process of step S1.

That is, in the cooling/heating mixed operation mode of Modification 2, first, the first control shown in step S7 is performed. A use of the heat medium heat exchanger 20c is determined. Here, the time condition shown in step S7_2 is, for example, the elapsed time from the start of the first control in step S7. When this elapsed time exceeds the threshold time, step S7_1 determines the use of the third heat medium heat exchanger 20c. Also, the specific threshold value shown in step S7_2 can be a value common to each indoor unit 3 .

Therefore, according to the air conditioner 100 according to Embodiment 1, when the cooling load is greater than the heating load, the third heat medium heat exchanger 20c is used for cooling, and when the cooling load is equal to or less than the heating load , the third heat medium heat exchanger 20c is used for heating. As a result, even when the load on the indoor unit 3 side is unbalanced, efficient operation according to the cooling or heating load can be performed, and comfort in the indoor unit 3 can be maintained.

In addition, the relay unit 2 incorporates three or more combinations of the pumps 21 and the heat medium heat exchangers 20, and according to the load on the indoor unit side, by using a plurality of pumps 21 on the high load side, Efficient operation can be performed accordingly. Furthermore, it is possible to eliminate the lack of ability (uncool and unwarm) and maintain comfort.

According to Embodiment 1, the heat medium heat exchanger 20 is selectively used for both cooling, heating, and cooling and heating during the cooling and heating mixed operation mode. A third heat medium flow switching device 28 is connected to the heat medium circulation circuit B for both cooling and heating, and a refrigerant flow switching device 24 is connected to the heat source side refrigerant circulation circuit A to cool the heat medium heat exchanger 20. It is used separately for the side and the heating side. As a result, the capacity in the cooling/heating mixed operation mode is improved, and comfortable operation can be provided regardless of the load on the indoor unit 3.

Embodiment 2.
FIG. 10 is a diagram showing the configuration of an air conditioner 100 according to Embodiment 2. As shown in FIG. The heat source side refrigerant circulation circuit A of the outdoor unit 1, the indoor unit 3, and the relay unit 2 is the same as in FIG. 2 of the first embodiment.

In Embodiment 1, as shown in FIG. 2, one pump 21 is provided upstream of each of the heat medium heat exchangers 20 . In Embodiment 2, as shown in FIG. 10, two pumps 21 (pump 21a, pump 21b) are connected to three heat medium heat exchangers 20 (first heat medium heat exchanger 20a, second heat medium heat exchanger). 20b, third heat medium heat exchanger 20c), two pumps 21 convey the heat medium.

In the second embodiment, the third heat medium flow switching device 28 (the third heat medium flow switching device 28a, the third heat medium flow switching device 28b) is composed of a three-way valve or the like, and in the cooling/heating mixed operation mode, The flow of the heat medium in the heat medium circulation circuit B is switched according to the load of .

The third heat medium flow switching device 28a is located downstream of each of the pumps 21a and 21b and upstream of the third heat medium heat exchanger 20c. The third heat medium flow switching device 28a flows the heat medium flowing into the pump 21a or the heat medium flowing into the pump 21b to the third heat medium heat exchanger 20c. Further, the third heat medium flow switching device 28b is provided downstream of the third heat medium heat exchanger 20c, and is downstream of each of the first heat medium heat exchanger 20a and the second heat medium heat exchanger 20b. connected to the side. The third heat medium flow switching device 28b switches the heat medium output from the third heat medium heat exchanger 20c to the heat medium main pipe 4 on the output side of the first heat medium heat exchanger 20a or the second heat medium heat exchanger. 20b into the heat medium main pipe 4 on the output side.

In the cooling/heating mixed operation mode, when the cooling load of the indoor unit 3 is greater than the heating load, the third heat medium flow switching device 28a and the third heat medium flow switching device 28b are switched to the cooling side, and the first heat medium flow switching device 28a and 28b are switched to the cooling side. The heat exchanger 20a and the third heat medium heat exchanger 20c are arranged in parallel. On the other hand, when the cooling load of the indoor unit 3 is equal to or less than the heating load, the third heat medium flow switching device 28a and the third heat medium flow switching device 28b are switched to the heating side, and the second heat medium heat exchanger 20b and the second heat medium heat exchanger 20b are switched to the heating side. 3 and the heat medium heat exchanger 20c are arranged in parallel.

The heat medium heat exchanger 20, the expansion device 22, the refrigerant flow switching device 24, and the third heat medium flow switching device 28 may be three or more.

FIG. 11 is a diagram showing a flowchart for explaining the operation in the cooling/heating operation mode of the air conditioner 100 according to the second embodiment.

In the cooling/heating mixed operation mode, the control device 50 controls the cooling load of the plurality of indoor units 3 and 3 is obtained (step S21). Here, the cooling load and heating load are capacities determined by the rating of the indoor unit 3 .

Next, it is determined whether the obtained cooling load is greater than the obtained heating load (step S22). If the cooling load is greater than the obtained heating load (YES in step S22), the control device 50 switches the third heat medium flow switching device 28a and the third heat medium flow switching device 28b to the cooling side ( step S23). On the other hand, if the cooling load is equal to or less than the heating load (NO in step S22), the control device 50 switches the third heat medium flow switching device 28a and the third heat medium flow switching device 28b to the heating side (step S24). ).

Next, it is determined whether the detection time has elapsed since the cooling/heating operation mode was started (step S25). If it is the detection time (YES in step S25), the difference between the suction temperature and the target temperature of the indoor unit 3 is the largest in accordance with the operation mode of the indoor unit 3, and the third heat medium heat exchanger 20c is turned on. It is used for cooling or heating (step S26). After that, the process returns to the process of step S21. If it is not the detection time (NO in step S25), the determination in step S25 as to whether it is the detection time is continued.

(Modification)
FIG. 12 is a flowchart of a modification that determines whether the third heat medium heat exchanger 20c is used for heating or cooling in the cooling/heating operation mode of the air conditioner 100 according to Embodiment 2. FIG. In FIG. 12, the description of steps that are the same as those in FIG. 11 will be omitted, and the different step S26_1 will be described here.

In step S26_1, the difference in the first detection time between the suction temperature measured by the temperature sensor 40 and the target temperature of the indoor unit 3, and the difference between the suction temperature measured by the temperature sensor 40 and the target temperature of the indoor unit 3 are detected. The third heat medium heat exchanger 20c is used for cooling or heating according to the operation mode of the indoor unit 3 among the plurality of indoor units 3 in which the difference from the difference at the second detection time after the first detection time is the smallest. use as After that, the process returns to the process of step S21.

Therefore, according to the air conditioner 100 according to Embodiment 2, compared to the air conditioner 100 according to Embodiment 1, it is possible to reduce the number of pumps 21 and reduce costs. Moreover, according to the air conditioner 100 according to Embodiment 2, even when the load is unbalanced, efficient operation can be performed according to the cooling or heating load, and comfort can be maintained on the load side.

Embodiment 3.
FIG. 13 is a diagram showing the configuration of an air conditioner 100 according to Embodiment 3. As shown in FIG. The outdoor unit 1 and the indoor unit 3 are the same as in FIG. 2 of the first embodiment.

In Embodiment 1, as shown in FIG. 2, a third heat medium heat exchanger 20c, an expansion device 22c, and a refrigerant flow switching device 24c are provided. In Embodiment 3, as shown in FIG. 13, the third heat medium heat exchanger 20c, expansion device 22c, and refrigerant flow switching device 24c are not provided.

In Embodiment 3, three pumps 21a, 21b and 21c transport the heat medium.

The third heat medium flow switching device 28a is provided on the upstream side of each of the pumps 21a and 21b, and between the first heat medium heat exchanger 20a, the second heat medium heat exchanger 20b, and the second heat medium heat exchanger 20b. It is connected to the upstream heat medium main pipe 4 . The third heat medium flow switching device 28a allows the heat medium flowing into the pump 21a or the heat medium flowing into the pump 21b to flow to the pump 21c. The third heat medium flow switching device 28b is connected to the heat medium main pipe 4 on the downstream side of the pump 21c, and is connected to the heat medium main pipes 4 on the downstream side of the pumps 21a and 21b. The third heat medium flow switching device 28b switches the heat medium flowing from the pump 21 to the heat medium main pipe 4 on the inflow side of the first heat medium heat exchanger 20a or the heat medium on the inflow side of the second heat medium heat exchanger 20b. It flows into the main pipe 4.

The pump 21a is provided in the main heat medium pipe 4 on the upstream side of the first heat medium heat exchanger 20a. The pump 21b is provided in the main heat medium pipe 4 on the upstream side of the second heat medium heat exchanger 20b. The pump 21c is provided in the main heat medium pipe 4 between the third heat medium flow switching device 28a and the third heat medium flow switching device 28b.

In the cooling/heating mixed operation mode, when the cooling load of the indoor unit 3 is greater than the heating load, the third heat medium flow switching device 28a and the third heat medium flow switching device 28b are switched to the cooling side, and the pump 21a and the pump 21c are parallel. On the other hand, when the cooling load of the indoor unit 3 is equal to or less than the heating load, the third heat medium flow switching device 28a and the third heat medium flow switching device 28b are switched to the heating side, and the pumps 21b and 21c are connected in parallel. .

The heat medium heat exchanger 20, the expansion device 22, the refrigerant flow switching device 24, and the third heat medium flow switching device 28 may be three or more.

FIG. 14 is a diagram showing a flowchart for explaining the operation in the cooling/heating operation mode of the air conditioner 100 according to the third embodiment.

In the cooling/heating mixed operation mode, the control device 50 controls the cooling load of the plurality of indoor units 3 and 3 is obtained (step S31). Here, the cooling load and heating load are capacities determined by the rating of the indoor unit 3 .

Next, it is determined whether the obtained cooling load is greater than the obtained heating load (step S32). If the cooling load is greater than the obtained heating load (YES in step S32), the control device 50 switches the third heat medium flow switching device 28a and the third heat medium flow switching device 28b to the cooling side ( step S33). On the other hand, if the cooling load is less than or equal to the heating load (NO in step S32), the control device 50 switches the third heat medium flow switching device 28a and the third heat medium flow switching device 28b to the heating side (step S34). ).

After step S33 or step S34, the pump 21 is driven (step S35).

Next, it is determined whether the detection time has elapsed since the cooling/heating operation mode was started (step S36). If it is the detection time (YES in step S36), the difference between the suction temperature and the target temperature of the indoor unit 3 is the largest, and the third heat medium heat exchanger 20c is operated according to the operation mode of the indoor unit 3. It is used for cooling or heating (step S37). After that, the process returns to the process of step S31. If it is not the detection time (NO in step S36), the determination in step S36 as to whether it is the detection time is continued.

(Modification)
FIG. 15 is a flowchart of a modification that determines whether the third heat medium heat exchanger 20c is used for heating or cooling in the cooling/heating operation mode of the air conditioner 100 according to Embodiment 3. FIG. In FIG. 15, the description of steps that are the same as those in FIG. 14 is omitted, and the different step S37_1 will be described here.

In step S37_1, the difference in the first detection time between the suction temperature measured by the temperature sensor 40 and the target temperature of the indoor unit 3, and the difference between the suction temperature measured by the temperature sensor 40 and the target temperature of the indoor unit 3 The third heat medium heat exchanger 20c is used for cooling or heating according to the operation mode of the indoor unit 3 among the plurality of indoor units 3 in which the difference from the difference at the second detection time after the first detection time is the smallest. use as After that, the process returns to the process of step S31.

Therefore, according to the air conditioner 100 according to the third embodiment, the number of the heat medium heat exchangers 20 is reduced to reduce the cost, and even when the load is unbalanced, efficient operation according to the cooling or heating load is performed. and maintain comfort on the load side.

In Embodiments 1 to 3, the third heat medium flow switching device 28a is also called an upstream heat medium flow switching device, and the third heat medium flow switching device 28b is also called a downstream heat medium flow switching device. The pump 21a is also called a first pump, the pump 21b is called a second pump, and the pump 21c is called a third pump.

In Embodiments 1 to 3, the case where there are two refrigerant pipes 5 flowing from the outdoor unit 1 to the indoor unit 3 has been described. The idea of controlling the heat medium heat exchanger 20 of the air conditioner 100 according to Embodiments 1 to 3 is to provide a forward pipe and a return pipe for cooling and a forward pipe and a return pipe for heating. It is also applicable to the air conditioner 100 using a tube chiller. Similarly, it can be applied to the air conditioner 100 for buildings using a three-pipe chiller.

The embodiments are presented as examples and are not intended to limit the scope of claims. Embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the gist of the embodiments. These embodiments and variations thereof are included within the scope and spirit of the embodiments.

1 outdoor unit, 2 relay unit, 3, 3a-3c indoor unit, 4 heat medium main pipe, 5, 5a, 5b refrigerant pipe, 6, 6a-6c, 6a_1, 6a_2, 6b_1, 6b_2, 6c_1, 6c_2 heat medium branch Piping, 7 Indoor space, 8 Space, 9 Building, 10 Compressor, 11 Refrigerant flow switching device, 12 Heat source side heat exchanger, 13 Accumulator, 14 Heat source side blower, 15 First connection pipe, 16 Second connection pipe, 17a to 17d first backflow prevention device, 20a first heat medium heat exchanger, 20b second heat medium heat exchanger, 20c third heat medium heat exchanger, 21, 21a to 21c pump, 22, 22a to 22c throttle device , 23, 23a, 23b opening/closing device, 24, 24a to 24c refrigerant flow switching device, 25, 25a to 25c first heat medium flow switching device, 26, 26a to 26c second heat medium flow switching device, 27, 27a to 27c heat medium flow control device, 28, 28a, 28b third heat medium flow switching device, 30, 30a to 30c indoor heat exchanger, 40, 40a to 40c temperature sensor, 50 controller, 100 air conditioner, A: Heat source side refrigerant circulation circuit, B: Heat medium circulation circuit.

Claims (6)

1. an outdoor unit having a compressor and outputting a refrigerant compressed by the compressor to a refrigerant pipe;
   a relay unit connected to the outdoor unit by the refrigerant pipe and exchanging heat between the refrigerant flowing through the refrigerant pipe and the heat medium flowing through the heat medium main pipe;
   an indoor unit having an indoor heat exchanger connected to the main heat medium pipe of the relay unit via a heat medium branch pipe;
   a controller for controlling the outdoor unit, the relay unit and the indoor unit;
   The relay unit is
   a first heat medium heat exchanger that exchanges heat between the refrigerant output from the outdoor unit to the refrigerant pipe and the heat medium flowing through the main heat medium pipe;
   a second heat medium heat exchanger that exchanges heat between the refrigerant output from the outdoor unit to the refrigerant pipe and the heat medium flowing through the main heat medium pipe;
   A third heat medium heat exchanger that exchanges heat between the refrigerant output from the outdoor unit to the refrigerant pipe and the heat medium flowing through the main heat medium pipe,
   a plurality of the indoor units,
   The control device is
   in a cooling/heating mixed operation mode, determining the cooling load of the plurality of indoor units and the heating load of the plurality of indoor units;
   When the determined cooling load is greater than the determined heating load, the third heat medium heat exchanger is used for cooling, and when the determined cooling load is equal to or less than the heating load, the Using the third heat medium heat exchanger for heating,
   The indoor unit includes a temperature sensor that measures a first temperature, which is the temperature of air heat-exchanging with the heat medium in the indoor heat exchanger,
   The control device is
   In the cooling/heating mixed operation mode, when the indoor unit having the largest difference between the first temperature measured by the temperature sensor and the target temperature of the indoor unit is performing the cooling operation, the third When the heat medium heat exchanger is used for cooling and the largest indoor unit is performing heating operation, a first control is performed to use the third heat medium heat exchanger for heating;
   Air conditioner.
2. an outdoor unit having a compressor and outputting a refrigerant compressed by the compressor to a refrigerant pipe;
   a relay unit connected to the outdoor unit by the refrigerant pipe and exchanging heat between the refrigerant flowing through the refrigerant pipe and the heat medium flowing through the heat medium main pipe;
   an indoor unit having an indoor heat exchanger connected to the main heat medium pipe of the relay unit via a heat medium branch pipe;
   a controller for controlling the outdoor unit, the relay unit and the indoor unit;
   The relay unit is
   a first heat medium heat exchanger that exchanges heat between the refrigerant output from the outdoor unit to the refrigerant pipe and the heat medium flowing through the main heat medium pipe;
   a second heat medium heat exchanger that exchanges heat between the refrigerant output from the outdoor unit to the refrigerant pipe and the heat medium flowing through the main heat medium pipe;
   A third heat medium heat exchanger that exchanges heat between the refrigerant output from the outdoor unit to the refrigerant pipe and the heat medium flowing through the main heat medium pipe,
   a plurality of the indoor units,
   The indoor unit includes a temperature sensor that measures a first temperature, which is the temperature of air heat-exchanging with the heat medium in the indoor heat exchanger,
   The control device is
   in a cooling/heating mixed operation mode, determining the cooling load of the plurality of indoor units and the heating load of the plurality of indoor units;
   When the determined cooling load is greater than the determined heating load, the third heat medium heat exchanger is used for cooling, and when the determined cooling load is equal to or less than the heating load, the Using the third heat medium heat exchanger for heating,
   A first temperature difference between the first temperature measured by the temperature sensor and a target temperature of the indoor unit at a first detection time, the first temperature measured by the temperature sensor, and the target temperature of the indoor unit. and a second temperature difference at a second detection time after the first detection time, and the indoor unit having the smallest difference between the first temperature difference and the second temperature difference performs the cooling operation. When the indoor unit is the smallest, the third heat medium heat exchanger is used for cooling, and when the smallest indoor unit is performing heating operation, the third heat medium heat exchanger is used for heating.
   Air conditioner.
3. The control device is
   After performing the first control in the cooling/heating mixed operation mode, if a time condition is satisfied, or if the temperature difference between the target temperature of the indoor unit and the first temperature measured by the temperature sensor is a specific threshold value. a first temperature difference between the first temperature measured by the temperature sensor and the target temperature of the indoor unit at a first detection time; the first temperature measured by the temperature sensor; A second temperature difference from the target temperature of the indoor unit at a second detection time after the first detection time is obtained, and the indoor unit having the smallest difference between the first temperature difference and the second temperature difference is determined. When the cooling operation is performed, the third heat medium heat exchanger is used for cooling, and when the smallest indoor unit is performing the heating operation, the third heat medium heat exchanger is used for heating. use as
   The air conditioner according to claim 1.
4. The relay unit is
   a first pump provided in the main heat medium pipe on the upstream side of the first heat medium heat exchanger;
   a second pump provided in the main heat medium pipe on the upstream side of the second heat medium heat exchanger;
   a third pump provided in the main heat medium pipe on the upstream side of the third heat medium heat exchanger;
   an upstream heat medium flow switching device provided in the heat medium main pipe on the upstream side of the first pump and the second pump;
   The air conditioner according to any one of claims 1 to 3, further comprising a downstream side heat medium flow switching device provided in the heat medium main pipe downstream of the first pump and the second pump. .
5. The relay unit is
   a first pump provided in the main heat medium pipe on the upstream side of the first heat medium heat exchanger;
   a second pump provided in the main heat medium pipe on the upstream side of the second heat medium heat exchanger;
   The third heat medium is provided in the heat medium main pipe on the downstream side of the first pump and the second pump, and the heat medium flowing into the first pump or the heat medium flowing into the second pump is used as the heat medium. an upstream heat medium flow switching device for flowing to the medium heat exchanger;
   Provided in the heat medium main pipe on the downstream side of the first pump and the second pump, the heat medium flowing out of the third heat medium heat exchanger is transferred to the heat medium on the output side of the first heat medium heat exchanger. The air conditioner according to any one of claims 1 to 3, further comprising a downstream side heat medium flow switching device that flows through the main medium pipe or the main heat medium pipe on the output side of the second heat medium heat exchanger. Device.
6. an outdoor unit having a compressor and outputting a refrigerant compressed by the compressor to a refrigerant pipe;
   a relay unit connected to the outdoor unit by the refrigerant pipe and exchanging heat between the refrigerant flowing through the refrigerant pipe and the heat medium flowing through the heat medium main pipe;
   an indoor unit having an indoor heat exchanger connected to the main heat medium pipe of the relay unit via a heat medium branch pipe;
   a control device that controls the outdoor unit, the relay unit, and the indoor unit;
   and
   The relay unit is
   a first heat medium heat exchanger that exchanges heat between the refrigerant output from the outdoor unit to the refrigerant pipe and the heat medium flowing through the main heat medium pipe;
   a second heat medium heat exchanger that exchanges heat between the refrigerant output from the outdoor unit to the refrigerant pipe and the heat medium flowing through the main heat medium pipe;
   a first pump provided in the main heat medium pipe on the upstream side of the first heat medium heat exchanger;
   a second pump provided in the main heat medium pipe on the upstream side of the second heat medium heat exchanger;
   an upstream heat medium flow switching device provided in the heat medium main pipe on the upstream side of the first pump and the second pump;
   a downstream side heat medium flow switching device provided in the heat medium main pipe downstream of the first pump and the second pump;
   a third pump provided in the main heat medium pipe between the upstream heat medium flow switching device and the downstream heat medium flow switching device;
   a plurality of the indoor units,
   The control device is
   in a cooling/heating mixed operation mode, determining the cooling load of the plurality of indoor units and the heating load of the plurality of indoor units;
   When the determined cooling load is larger than the determined heating load, the upstream heat medium flow switching device and the downstream heat medium flow switching device are controlled to the cooling side, and the third pump is used for cooling, and when the obtained cooling load is equal to or less than the heating load, the upstream heat medium flow switching device and the downstream heat medium flow switching device are controlled to the heating side, and the using the third pump for heating,
   Air conditioner.

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